Air flow measuring device formed integrally with electronically controlled throttle body

ABSTRACT

An air flow sensor for an internal combustion engine is disclosed. An air flow rate measurement meter, a pressure gauge, electronically controlled throttle body, and the microcomputer, etc. are integrated as one body, and the correction of the air flow rate, the control, and the fault diagnosis, etc. are done in the integrated microcomputer. 
     The air flow sensor outputs an air flow rate signal in which the error is deleted to suppress the discharge of the harmful exhaust gas from the internal combustion engine, carries out the self-diagnosis of the breakdown of the air flow sensor or the electronically controlled throttle body to prevent the accident beforehand, and controls to obtain the best intake air amount.

TECHNICAL FIELD

The present invention relates to an air flow sensor, and particularly toan electronically controlled throttle body integrated air flow sensorwhich controls the amount of intake air in an internal combustionengine.

BACKGROUND ART

The prior art concerning the integration of the electronicallycontrolled throttle body and the air flow sensor is disclosed in theJapanese Patent Application Laid-Open No. 4-350338.

Although the throttle valve opening controller of the electronicallycontrolled throttle body and the air flow sensor are installed in thesame body respectively in this prior art, they are functionallyindependent of each. Although a lot of errors are included in the airflow rate output signal of this air flow sensor usually, this outputsignal is supplied to the engine control unit as it is. Further, becausethe information interchange is not mutually done between the throttlevalve opening information and the air flow rate signal, it is impossibleto perform the self-fault diagnosis. In addition, it is not possible toperform the feedback-control of the throttle valve to become the bestintake air flow, because the intake air flow signal is not input to thethrottle valve controller in the conventional configuration.

In the air flow sensor, the amount of the intake air to the internalcombustion engine is detected by a small detector compared with the airpassage. Therefore, the error occurs in the air flow rate output signalof the air flow sensor when the turbulence or the drift or the backflowis caused even if the mass of air which flows in the air passage is thesame. Because the output signal with this error is sent to the enginecontrol unit, combustion cannot be controlled best. Therefore, theharmful exhaust gas is discharged.

A serious problem is caused due to the breakdown of the electronicallycontrolled throttle body, so that the engine goes out of control.Therefore, the double or triple safety system and the fault diagnosissystem are demanded. Further, the breakdown of the air flow sensorcauses the internal combustion engine for the harmful exhaust gas to bedischarged as mentioned above. In addition, it is required to control soas to obtain the best intake air flow, not to control according to theamount of the accelerator stepping, in order to suppress the dischargeof such harmful exhaust gas

DISCLOSURE OF INVENTION

An object of the present invention is to provide an electronicallycontrolled throttle body integrated air flow sensor, in which the airflow rate signal with extremely few errors is output to suppress thedischarge of the harmful exhaust gas from the internal combustionengine, and the best amount of intake air is supplied to the internalcombustion engine.

Another object of the present invention is to provide an electronicallycontrolled throttle body integrated air flow sensor, in which it ispossible to perform the self-diagnosis of the breakdown of the air flowsensor or the electronically controlled throttle so that the accidentcan be prevented beforehand.

In the device according to one aspect of the present invention, the airflow meter, the pressure gauge, the electronically controlled throttlebody, and the microcomputer, etc. are integrated as one. The correction,the control, and the fault diagnosis of each measurement of the air flowrate etc. are done by the integrated microcomputer. It, therefore,becomes possible to produce the air flow sensor which can measure anaccurate air flow rate at low man-hour and low-cost. The correction ofthe measurement to control the entire internal combustion engine or theentire car and the self-diagnosis done by the control unit so far iscarried out by the air flow sensor itself. Therefore, the load ofcontrol unit is decreased. Further, wiring and a lot of power suppliesbecome unnecessary because the information on throttle valve openingnecessary for the correction can be obtained internally. Therefore,making to low-cost and the miniaturization become possible. Further, thematching man-hour can be decreased by setting the correction factorbeforehand before building in the system.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing one embodiment of the present invention, and across-sectional view showing the configuration of the integrated airflow sensor in which the control module provided with a microcomputer isintegrated with the electronically controlled throttle body.

FIG. 2 is an outview in which the air flow sensor of FIG. 1 is seen fromthe upper part of space.

FIG. 3 is a block diagram to explain the operation of the air flowsensor of FIG. 1.

FIG. 4 is a cross-sectional view of the conventional electronicallycontrolled throttle body integrated air flow sensor.

FIG. 5 is an outview in which the conventional air flow sensor of FIG. 4is seen from the upper part of space.

FIG. 6 is a block diagram to explain the operation of the conventionalair flow sensor shown in FIG. 4.

FIG. 7 is a flow chart of the operation of an electronically controlledthrottle body integrated air flow sensor according to one embodiment ofthe present invention.

FIG. 8 is a flow chart of the operation of an electronically controlledthrottle body integrated air flow sensor according to one embodiment ofthe present invention.

FIG. 9 is a flow chart of the electronically controlled throttle bodyintegrated air flow sensor according to one embodiment of the presentinvention.

FIG. 10 is an explanatory drawing to calculate the engine speed.

FIG. 11 is a flow chart to calculate the engine speed.

FIG. 12 is an explanatory drawing to calculate the engine speed.

FIG. 13 is a circuit diagram of the air flow sensor which explains thefunction to calculate the temperature of air in the electronicallycontrolled throttle body integrated air flow sensor.

FIG. 14 is a flow chart of the operation of the electronicallycontrolled throttle body integrated air flow sensor according to oneembodiment of the present invention.

FIG. 15 is a timing chart which explains one embodiment of the presentinvention.

FIG. 16 is a flow chart of the operation of an electronically controlledthrottle body integrated air flow sensor according to one embodiment ofthe present invention.

FIG. 17 is a timing chart which explains one embodiment of the presentinvention.

FIG. 18 is a system configuration chart according to one embodiment ofthe present invention.

FIG. 19 is a flow chart of the operation of an electronically controlledthrottle body integrated air flow sensor according to one embodiment ofthe present invention.

FIG. 20 is a cross-sectional view of an electronically controlledthrottle body integrated air flow sensor according to one embodiment ofthe present invention.

FIG. 21 is a flow chart of the operation of the electronicallycontrolled throttle body integrated air flow sensor according to oneembodiment of the present invention.

FIG. 22 is a flow chart showing the computational procedure.

FIG. 23 is a model chart showing the operational state of theelectronically controlled throttle body integrated air flow sensoraccording to one embodiment of the present invention.

FIG. 24 is an illustration of the system of the internal combustionengine which uses an electronically controlled throttle body integratedair flow sensor according to one embodiment of the present invention.

BEST MODES FOR IMPLEMENTING THE INVENTION

The embodiments of the present invention is explained with reference toFIG. 1 through FIG. 24.

FIG. 1 is a cross section showing the configuration of one embodiment ofthe throttle body integrated air flow sensor according to the presentinvention. FIG. 2 is an outview in which the air flow sensor of FIG. 1is seen from the upper part of space.

Electronically controlled throttle body integrated air flow sensor 12has electronically controlled throttle body 14 which forms main airpassage 7 which is a part of suction passage of the engine and to whicheach part is fixed, air flow sensor 13 which has thermosensitiveresistor 4 which is the air flow rate detection element arrangedinternally in main air passage 7, electronically controlled throttlemotor 11, throttle valve 10 which rotates centering on throttle shaft 9arranged in main air passage 7, and controls the open/close of the mainair passage 7, throttle valve opening sensor 16 which detects opening ofthrottle valve 10. In addition, control module 2 in which microcomputer1 for correcting the air flow rate signal obtained by air flow sensor13, and controlling throttle valve 10, etc. are built-in them.

Air flow sensor 13 provided in the upstream of throttle shaft 9 detectsthe air flow rate of air stream 8 in main air passage 7 of which airflow rate is controlled by throttle valve 10. Here, a heat resistancetype air flow sensor is explained as an example of the air flow sensor,which has sub-air passage 6, and has heat resistor 4 and thermosensitiveresistor 5 for measuring the air flow rate inside of the sub-airpassage.

Heat resistor 4 and thermosensitive resistor 5 are fixed to supportmember 15, and connected electrically with control module 2 outside ofmain air passage 7. Control module 2 has an electronic circuit forcontrolling the heating of heat resistor 4, and microcomputer 1 whichcorrects the obtained air flow rate signal based on the amount of heatradiation from heat resistor 4 to air.

This microcomputer 1 not only corrects the air flow rate signal but alsocontrols motor 11 for rotating throttle shaft 9 based on a signal fromthrottle valve opening sensor 16, etc. In addition, this microcomputer 1has the functions of operation of the self-diagnosis and the intaketemperature, etc. as described later.

Further, connector 3 for inputting signals from the outside such as theengine speed and the accelerator pedal opening, and for outputtingsignals such as the air flow rate and the throttle valve opening, etc.to control unit (ECU) is provided in control module 2.

Because the detection, the correction, and the control of the intake airflow are performed by one unit in this invention, the closed correctionand control in the unit becomes possible as described later. Further,the improvement of the installation to the engine, the reduction of thewire harness becomes, and the integration of electronic circuit becomespossible. It will not be necessary to provide with the power supply andthe electric wave parts separately when electronic circuits areintegrated.

FIG. 3 shows the block diagram of FIG. 1. Microcomputer 1 in controlmodule 2 corrects the air flow rate based on air flow rate signal 113output from air flow sensor 13, and outputs the corrected air flow ratesignal 113 b to the external ECU26 in the electronically controlledthrottle body integrated air flow sensor 12. Further, microcomputer 1controls motor 11 which synchronizes with the throttle valve by motorcontrol signal 111 according to throttle valve opening signal 116obtained by throttle valve opening sensor 16 based on accelerator pedalopening signal 125 measured by accelerator pedal opening sensor 25obtained from the outside. Further, these are driven by power supply 24.

FIG. 4 is a cross-sectional view of the conventional electronicallycontrolled throttle body integrated air flow sensor. FIG. 5 is anoutview in which the conventional air flow sensor of FIG. 4 is seen fromthe upper part of space.

Electronically controlled throttle body integrated air flow sensor 12 isprovided with air flow sensor 13, circuit module 2 a for controlling it,microcomputer 1 a, connector 3 a, electronically controlled throttlebody 14, throttle shaft 9, throttle valve opening sensor 16, motor 11,and connector 3 b.

Connector 3 a outputs the air flow rate measured by electronicallycontrolled throttle body integrated air flow sensor 12 to an externalelectronic control unit.

Connector 3 b outputs throttle valve opening signal 116 obtained bythrottle valve opening sensor 16 to an external control module which hasan microcomputer, and receives a motor control signal from the controlmodule.

FIG. 6 is a block diagram illustrating the operation of the conventionalair flow sensor shown in FIG. 4.

Air flow rate 113 a is measured by air flow sensor 13 in electronicallycontrolled throttle integrated air flow sensor 12, and is corrected bymicrocomputer 1 a in control module 2 a. That is, it is possible tocorrect easily only by the air flow sensor unit. For instance, air flowrate signal 113 b to which only the influence of the backflow iscorrected is sent to external ECU 26. Further, throttle valve openingsignal 116 detected by throttle valve opening sensor 16 inelectronically controlled throttle integrated air flow sensor 12 is sentto external control module 2 b and ECU 26.

ECU 26 corrects an accurate air flow rate by using throttle valveopening signal based on air flow rate signal 113 b.

On the other hand, electronically controlled throttle motor 11 iscontrolled by motor control signal 111 in control module 2 b and ECU26based on accelerator opening signal 125 measured by the acceleratorpedal opening sensor. Further, air flow sensor 13 and electronicallycontrolled throttle body 14 are driven in separate power supplies 24.

Because, in the prior art, the amendment of the air flow rate and themotor control are carried out by the ECU, the ECU is under the overload,or the control module which has another microcomputer for the throttlecontrol is needed. Further, there are a lot of wirings because allinformation is sent to the ECU.

Further, because the control circuits is separate, the power supply andthe radio shielding parts are required for each circuit.

The embodiment of the correction means for the air flow rate measurementvalue and the throttle valve opening control means in the electronicallycontrolled throttle body integrated air flow sensor according to thepresent invention is explained by using the flow chart of FIG. 7.

When the air flow sensor is integrated with the throttle body, differentdrifts are occurred in the main air passage of the air flow detectionportion of the air flow sensor according to the throttle valve opening.Therefore, an error is easily occurred in the air flow detection value.It becomes possible to correct the air flow rate detection value basedon the throttle valve if the measurement error of the air flow rate bythrottle valve opening is known beforehand, because air flow rate signal113 output from the air flow sensor and throttle valve opening signal116 are input to microcomputer 1 in the present invention.

The electronically controlled throttle motor is driven, receiving motorcontrol signal 111 determined in microcomputer 1 based on inputaccelerator opening signal 125, etc. The opening of the throttle valveis controlled by the motor drive. Further, the opening of the throttlevalve is detected by the throttle valve opening sensor, and isfeedback-controlled to always become appropriate for controlled variableof microcomputer 1. In the present invention, air flow rate signal 113 ais corrected by using this throttle valve opening signal 116. Thiscorrection is made by using a map, etc. of the air flow rate detectionerror concerning the throttle valve opening, the air flow rate value,and their combination condition. The corrected air flow rate signal 113b is output to the ECU as an air flow rate signal detected by theelectronically controlled throttle body integrated air flow sensor.Therefore, the air flow rate value to which the influence by throttlevalve opening is greatly decreased by an internal correction isobtained, and a highly accurate engine control becomes possible in theelectronically controlled throttle body integrated air flow sensor ofthe present invention.

On the other hand, it may be necessary to control the throttle valveopening based on the air flow rate signal to obtain the target air flowrate, in order to perform the control of the air flow rate when theengine is under an idling state, the decrease of the torque shock whenthe accelerator changes suddenly, and the control of the air flow ratematched to the amount of fuel supplied to the engine, although throttlevalve opening is usually mainly controlled by the accelerator openingsignal.

The control of throttle valve opening by the air flow rate becomespossible in the electronically controlled throttle body integrated airflow sensor, because motor control signal 111 which is the controlledvariable of the electronically controlled throttle motor can bedetermined based on air flow rate signal 113 b to which theabove-mentioned correction is made as shown in FIG. 7.

Next, one embodiment is explained by using FIG. 8, in which anappropriate air flow rate can be output or fault self-diagnosis can beperformed by an electronically controlled throttle body integrated airflow sensor of the present invention when a certain kind of abnormalityis caused.

The air flow rate signal output to the ECU is air flow rate signal 113 aitself obtained by the air flow sensor, or corrected air flow ratesignal 113 b based on throttle valve opening as mentioned above. The ECUperforms the engine control of fuel injection quantity, etc. based onthis signal. Therefore, when the air flow sensor outputs an abnormalsignal due to the breakdown etc., the proper engine control is failed.When the air flow rate signal is outside usual output ranges of 0V or 5Vor more, etc., the air flow sensor is diagnosed as the fault, or thebreakdown of the air flow sensor is diagnosed based on the comparisonwith the detection signal of the density of oxygen in exhaust gas.

It is possible to obtain air flow rate QαN 113 a′ by a so-called α-Nmethod besides the air flow rate measured by the air flow sensor byusing throttle valve opening signal 116 which the device itselfpossesses and engine speed signal 120 obtained from the outside or theinside, by the microcomputer in an electronically controlled throttlebody integrated air flow sensor according to the present invention. Inaddition, the corrected second air flow rate signal QαN 113 b′ which itcompares and contrasts easily to the corrected mass flow rate Qafs 113 bmeasured by the heat resistor type air flow sensor, by correcting theair flow rate based on the air temperature signal 105 obtained from theoutside or the inside.

Therefore, the first air flow rate Qafs thought to be more highlyaccurate is output as an air flow rate signal when the differencebetween the first air flow rate Qafs obtained by the air flow sensor andthe 2nd air flow rate QαN, obtained by the comparison operation is thefixed value or less.

Fault signal 21 which informs the breakdown of this device is sent tothe outside, for example, ECU 26 when the difference more than a certainpredetermined value is generated.

This fault signal 21 can be assumed to be a signal with an easybreakdown judgment by the electronic control unit by assuming the airflow rate signal to be 0V for instance even if another signal wire isnot provided.

Further, the safety faction concerning the throttle control is backed upenough.

Therefore, when abnormality is not admitted in the throttle valvecontrol by other diagnoses, it is also possible to judge that it is abreakdown of the air flow sensor, and to output the second air flow rateQαN as the air flow rate signal.

In addition, the heat resistance type air flow sensor etc. might causethe error in the measured air flow rate by the pulsation flow and thebackflow, etc. caused in the main air passage in the air flow ratemeasurement portion when throttle valve opening is large. Therefore, itis possible to output the second air flow rate QαN as the air flow ratesignal by switching to the second air flow rate without diagnosing thefailure when the throttle valve opening is more than the predeterminedvalue.

Here, a means for obtaining the pressure by using the second air flowrate QαN is explained with reference to FIG. 8. The second air flow rateQαN obtained by the same method as the above-mentioned embodiment is avolumetric flow rate. On the other hand, the first air flow rate Qafsobtained by the heat resistance type air flow sensor is a mass flowrate. Therefore, there is a difference of the measurement according tothe temperature and pressure between the two. That is, the air pressureis obtained by dividing the mass flow rate by the volumetric flow rate,and air pressure is obtained by multiplying the ratio of the air densityin standard condition which is already-known as the physical propertiesvalue, the ratio of the air temperature signal 115 which is the intaketemperature obtained from the outside or the inside to the ratio of thestandard temperature, and the standard pressures. As a result, theoutput to the ECU, etc. becomes possible.

FIG. 10 is an explanatory drawing of the method of calculating theengine speed from the air flow rate signal.

As a result, the calculation of the engine speed becomes possible by anelectronically controlled throttle body integrated air flow sensor. Theaxis of ordinate designates an air flow rate signal of the air flowsensor in the suction stroke of the engine, and the axis of abscissadesignates time.

When the engine is driven at a constant revolution speed, the air flowrate signal of the air flow sensor shows the constantly periodicpulsation like the sine wave. The reason for this is that the intake airamount increases gradually when the suction stroke is started, and itdecreases gradually when the suction stroke advances to some degree.

In the present invention, the method of obtaining the engine speed frompulsation waveform generated in this suction stroke is adopted.

Namely, as shown in FIG. 10, the engine speed when the intake air ispulsated can be led by counting the time (Taw) from the time when thepulsation waveform of the air flow rate signal to lead the engine speedexceeds the mean value of the air flow rate signal in one-suction-strokeprevious stroke (section a) to the time when it exceeds the mean valuein the suction stoke (section b) of the following cylinder, andcalculating backward according to the number of cylinders of engine byusing this time.

In a word, the transition duration of the suction stroke betweencylinders is measured.

The formula by which the engine speed is led from the transitionduration of the suction stroke between cylinders is as follows.

NE=60/Taw*Nci

NE: Engine speed (r/min)

Taw: Transition duration of the suction stroke between cylinders (s)

Nci: The number of cylinders.

FIG. 11 is a flow chart illustrating the operation when the engine speedis obtained from the air flow rate signal.

Air flow rate signal Qsamp is converted to numeric value by an A/Dconverter, etc.

The converted air flow rate value Qsamp is stored in the memory to takeaverage Qave in a constant section. At the same time, Mean value Qaveoldof the intake air flow rate calculated previously from this suctionstroke and the air flow rate value Qsamp taken at this time is compared.

As a result, if the air flow rate value Qsamp taken at this time issmaller than the previous mean value Qaveold, the count of time is notcarried out.

In addition, the air flow rate signal is taken, and when the air flowrate value Qsamp taken at this time becomes larger than the averagevalue Qaveold, the count of is started.

The intake air attenuates gradually and is succeeded to the followingsuction stroke as explained previously. The count is stopped and thetime of the suction stroke is stored as data when the air flow ratevalue Qsamp taken in this attenuation process reaches a smaller valuethan the mean values Qaveold, and it becomes a value which exceeds themean value again.

Here, the mean value Qave of air flow rate value Qsamp which has beenmeasured before is calculated at the same time, the measurement isprepared for the next suction time, and the time counter is initialized.

Thus, the second air flow rate QαN described before is calculated byusing the engine speed obtained like this.

The engine speed can be obtained even by another method.

The present invention has the function that the engine speed can becalculated by using the change in the intake air pressure in the mainair passage of the electronically controlled throttle body integratedair flow sensor in which the pressure sensor described later isintegrated.

It is possible to calculate this engine speed by detecting the state inwhich the pressure fluctuation of the intake air changes according tothe pulsation of the intake air of the engine like the air flow ratesignal.

The fluctuation of pressure pulsates similarly almost with the outputsignal of air flow sensor shown in FIG. 10, in which the ordinatedesignates the pressure fluctuation of the intake air and the abscissadesignates time as shown in FIG. 12.

Therefore, the engine speed can be calculated by using the sameprocedure as when the engine speed was obtained from the air flow rate,and the second air flow rate QαN can be calculated in the electronicallycontrolled throttle body integrated air flow sensor itself.

Next, the method by which the intake temperature necessary for thecorrection of the second air flow rate QαN previously described etc. iscalculated by the electronically controlled throttle body integrated airflow sensor.

The principle of operation of the heat resistor type air flow sensor isto detect the power consumption when giving the arbitrary calorificvalue, that is, temperature difference to the intake temperature.

In a word, the intake temperature is always detected.

The basic component of a typical driving circuit of the heat resistortype air flow sensor is shown in FIG. 13.

The resistance of thermosensitive resistor 5 is decided in accordancewith the temperature of the intake air to which thermosensitive resistor5 is exposed, when the arbitrary voltage is applied to thermosensitiveresistor 5 for detecting the intake temperature shown in FIG. 13, andelectric current 18 C corresponding to the temperature flows based onOhm's law.

The heat voltage to apply to heat resistor 4 by a constant magnificationis feedback-controlled based on the electric current 18C which flowsaccording to the intake temperature.

Then, the control circuit detects current value 18 h flowing throughheat resistor 4. As a result, the air flow rate which flows to thesurroundings of the air flow sensor can be obtained.

This is the principle of operation of the heat resistor type air flowsensor.

Then, the intake temperature can be easily obtained by detecting theelectric current which flows to the thermosensitive resistor previouslyexplained, and converting it into the intake temperature by thearithmetic circuit.

In one example of the present invention, the error of the air flowsensor occurred by intake temperature is corrected by using the intaketemperature obtained by detecting the electric current which flows tothe thermosensitive resistor as described above.

FIG. 14 is a flow chart illustrating the operation of one embodiment ofthe present invention. FIG. 15 is its timing chart. In FIG. 15, theordinate designates the throttle valve opening, the air flow ratesignal, and the air flow rate signal after the filter is put, and theabscissa designates time.

The electronically controlled throttle body calculates the best openingof the throttle means, for instance, throttle valve opening by thearithmetic circuit provided in said electronically controlled throttlebody based on the accelerator pedal opening signal which is proportionalto the opening of the accelerator pedal, and controls the throttle valveopening by the motor etc. Next, throttle valve opening provided on saidelectronically controlled throttle body is detected, whether thethrottle valve opening is appropriate opening based on the signal of thethrottle valve opening sensor is detected, and when not appropriateopening, the feedback control is performed to obtain appropriateopening.

Here, if there is no change or very small change in said acceleratoropening signal in the unit time, by which the signal of said throttlevalve opening sensor or the opening of the throttle valve is decided,the change in the actual air flow rate is not or is small. However, thenoise due to the pulsation or the electric noise is superimposed to theair flow rate signal of the air flow sensor, and it outputs as if airflow rate is changed.

According to this embodiment, that the change dPs or dPt in the unittime is zero or is small is detected based on the signal Ps of saidthrottle valve opening sensor or the signal Pt of said accelerator pedalopening sensor which decides the opening of the throttle valve. And,these noises can be removed by selecting the integrator which integrates(filters) the air flow rate signal of the air flow rate measurement partby the arithmetic circuit according to dPlos or dPt, and outputting theintegral value. Therefore, a more highly accurate and stable intake airflow signal can be output.

A method in which plural integrators of hardware type in which theelectronic components and electrical components are combined areprovided as said integrator each integration time constant, and theintegrator with the time constant suitable for the throttle valveopening speed or the accelerator pedal opening speed is selected, or amethod in which the integrator of software type which averages the airflow rate signal according to the throttle valve opening speed or theaccelerator pedal opening speed is used or both of hardware type andsoftware type are used in combination can be adopted.

In this embodiment, the software type is used.

FIG. 16 shows the flow chart of the operation of the electronicallycontrolled throttle body integrated air flow sensor according to oneembodiment of the present invention. FIG. 17 shows its timing chart. Theair flow rate signal is output through the integrator in the embodimentshown in FIG. 14. However, the response delay occurs for the change inthe actual air flow if the integrator is added for the air flow ratesignal when the throttle valve opening speed is fast.

According to this embodiment, the throttle valve opening speed isdetected by comparing the change in the unit time for said throttlevalve opening speed, and the signal of said throttle valve openingsensor or the signal of said accelerator pedal opening sensor whichdecides the opening of the throttle valve. When the detected throttlevalve opening speed is faster than a fixed value, the air flow ratesignal is directly output without passing through the integrator. Whenthe throttle valve opening speed is far faster than the fixed value, thephysical response delay of the heat resistor, for example, the delay forthe actual air flow rate due to the delay of the thermal conduction orthe heat transmission is occurred. As a result, the output of the airflow rate signal has the error corresponding to the amount of the delay.Therefore, if the throttle valve opening speed is far faster than thepredetermined value, the fixed value is added by passing thedifferentiators or by passing the air flow rate signal through the addercircuit, and the corrected signal is output. As a result, a highlyaccurate stable intake air flow rate signal close to the actual air flowrate can be output.

A method in which plural differentiators of hardware type in which theelectronic components and electrical components are combined areprovided as said differentiator each differential constant, thedifferential constant suitable for the throttle valve opening speed orthe accelerator pedal opening speed is calculated by the arithmeticcircuit and the differentiator with suitable differential constant isselected, or a method in which the differentiator of software type whichadds the value corresponding to the throttle valve opening speed or theaccelerator pedal opening speed to the air flow rate signal is used orboth of hardware type and software type are used in combination can beadopted.

A method in which plural adders of hardware type in which the electroniccomponents and electrical components are combined are provided as saidadder each adding constant, the adding constant suitable for thethrottle valve opening speed or the accelerator pedal opening speed iscalculated by the arithmetic circuit and the adder with suitable addingconstant is selected, or a method in which the adder of software typewhich adds the value corresponding to the throttle valve opening speedor the accelerator pedal opening speed to the air flow rate signal isused or both of hardware type and software type are used in combinationcan be adopted.

Next, one embodiment of the electronically controlled throttle bodyintegrated air flow sensor which can support a variety of engine layoutsis explained with reference to FIG. 18 and FIG. 19.

Even if the air flow rate is the same, there is an error in the air flowrate value when the drift is caused in the element because the air flowrate is measured by small elements such as a heat resistor. The factorthat the drift is caused is generated by the change in the form of theduct installed at the above-mentioned throttle valve position in theupstream of the air flow sensor or the position of said throttle valve.Therefore, the correction according to the duct form or the change inthe output basis data of the air flow sensor is required.

The electronically controlled throttle body integrated air flow sensorof the present invention has two or more correction maps or basic datawhich correspond to the duct form change to support to a variety ofengine layouts. Although the maps or basic data for the correction isfor the duct form, it may prepare the map for the change in fuel costand output.

The selection of the plural maps or basic data can be done freely or setonly once or changed by using a specific condition, for instance, aspecial tool or password.

The system configuration of said plural-basic data selection part of theelectronically controlled throttle body integrated air flow sensor ofthe present invention is shown in FIG. 18.

Basic data is stored in a nonvolatile memory arranged in the controlmodule, for example, ROM. At least one correction map is stored.

The basic data can be selected after the completion by using a memorywhich can read/write electrically, for example, a flash memory, anEEPROM, a fuse ROM, and zener zap, etc. different from the previous ROMas the control module.

The writing of data to the memory which can write electrically isperformed by using the control module.

The control module limits so that the basic data described above may benot selected over a plurality of times in the present invention. Thepurpose of this is to avoid the data in use as a product being rewrittenby some factors.

As a concrete method, 225 kinds of means as the write-protection methodsuch as a method of mechanically intercepting the signal path ofwriting, and a method of protecting the writing by the content of theoperation in the control module.

That is, there is a method of mechanically intercepting the writingroute by fusing the writing limitation fuse shown in FIG. 18. Inaddition, there is a method of inhibiting the rewriting of the flashmemory in the future by writing certain one data in the flash memory inthe predetermined pattern for instance.

It is necessary to write the data by the control module in case of thewriting means which requires the processing of software such as a flushmemory and an EEPROM. However, it is not required to protect the writingin case of a means in which the data can be directly written intowithout the internuncial software like the fuse ROM, the zener zap, etc.

Further, rewriting basic data might be actually unavoidably needed inusing the product.

The data can be rewritten by using a certain special means in thepresent invention for this.

A flow chart of the way to demand the input of the password when writingagain is shown in FIG. 19 as one embodiment to achieve such theconfiguration.

The control module demands the external adjustment circuit the input ofthe password as a condition necessary for writing when entering thewriting mode. When the password is not input from the adjustmentcircuit, the control module shifts to a usual operational state andbegins normal operation.

When the password is input from the adjustment circuit to the controlmodule, it shifts to the state that basic data can be selected andwrites the data in the memory which can write data electricallydescribed above. Further, only a specific person can change by using themethod of selecting correction value in software, for example, the useof the password and a method of selecting mechanically by using thescrewdriver of which the point is formed in star-shape not used ingeneral.

FIG. 20 is a cross section showing the configuration of one embodimentof the throttle body integrated air flow sensor of the present inventiondifferent from FIG. 1. The difference with FIG. 1 is in the point thatpressure measurement device 17 has been installed in control module 2and that pressure inlet 29 for introducing the pressure of main airpassage 7 in the downstream of the throttle valve to pressuremeasurement device 17. Other configurations and effects are the same asthe electronically controlled throttle body integrated air flow sensorexplained by using FIG. 1-FIG. 3.

The measurement of the atmospheric pressure becomes possible if pressureintroducing inlet 29 is provided so as to open toward the outside of thethrottle body although such the configuration is not shown in thisembodiment. In addition,

By opening this inlet toward both of the main air passage and theoutside and by enabling the selection of the aperture by using a switchvalve, the pressure in the main air passage in the downstream of thethrottle body and the atmospheric pressure can be measured by onepressure measurement device.

In the electronically controlled throttle body integrated air flowsensor of the present invention, the control of the throttle valvecontrol according to the correction of the pressure signal and thepressure signal becomes possible as well as the correction means of theair flow rate measurement value and the throttle valve opening controlmeans explained with reference to FIG. 7. This will be explained withreference to FIG. 21.

When the pressure measurement device is integrated with the throttlebody, it may be necessary to provide the opening end of the pressureintroducing inlet in the neighborhood of the throttle valve. Therefore,the error is caused easily in the pressure detection value because thedrift is caused in the main air passage in the installation part of thepressure introducing inlet similarly to causing the different driftaccording to throttle valve opening in the main air passage of the airflow rate sensing part in the air flow sensor. According to the presentinvention, if the pressure measurement error corresponding to thethrottle valve opening is known beforehand because pressure signal 117 aoutput from the pressure measurement device and throttle valve openingsignal 116 are input to microcomputer 1, the correction of the pressuredetection value becomes possible based on throttle valve opening. Theopening of the throttle valve is controlled by the electronicallycontrolled throttle motor driven by receiving motor control signal 111decided by microcomputer 1 based on the input accelerator opening signal125, etc. The opening of the throttle valve is detected by the throttlevalve opening sensor, and feedback-controlled so as to always beappropriate to the controlled variable of microcomputer 1. In thepresent invention, the pressure signal 117 a is corrected by usingthrottle valve opening signal 116 and a map showing the errors of thepressure detection under the conditions of the throttle valve opening,the pressure and the their combination. The corrected pressure signal117 a is output to the ECU as the pressure signal detected in thethrottle valve opening. Therefore, according to the electronicallycontrolled throttle body integrated air flow sensor of the presentinvention, the pressure value in which the influence by throttle valveopening is decreased by the internal correction can be obtained, and ahighly accurate engine control becomes possible.

Further, the control of the throttle valve opening by the pressurebecomes possible in the electronically controlled throttle bodyintegrated air flow sensor because the controlled variable of theelectronically controlled throttle motor can be determined based on thecorrected pressure signal, as shown in FIG. 21.

One embodiment of the present invention in which the correction of theair flow rate measurement value, the fault diagnosis or the judgment ofthe best air flow rate is performed by the electronically controlledthrottle body integrated air flow sensor will be explained next.

FIG. 22 is a flow chart illustrating the main calculation procedure.

The air flow rate values obtained by the following three differentmethod are compared after correction and judged. Namely, the air flowrate value 113 a (Qafs) per the specific revolution speed obtained fromthe engine speed signal 120 and the output signal of the air flowsensor; the air flow rate value 113 a″ (QNρ) per the same specificrevolution speed obtained from the intake manifold pressure output bythe pressure sensor, the atmospheric pressure, the air temperaturesignal 105, and the engine speed signal 120; and the air flow rate value113 a′ (QαN) per the same specific revolution speed obtained fromthrottle valve opening signal 116 of the throttle valve opening sensor,the atmospheric pressure signal, the air temperature signal 105, and theengine speed signal 120.

In this comparison and judgment, the correction value is not calculatedwhen three kinds of air flow rate values are almost equal for instance(It is in the unnecessary-correction range), Qafs is output to the ECUas an air flow rate signal. The correction value of the Qafs iscalculated when the Qafs is different from the other two kinds (QNρ andQαN). If it is a range of non-breakdown judgment, Qafs is output to theECU. If it is a range of the breakdown judgment, fault signal 21 isoutput and the air flow rate value other than Qafs is output to the ECU.When QNρ or QαN is different from the other two kinds, the correctionvalue is calculated, fault signal 21 is output, and Qafs is output tothe ECU.

Therefore, because the correction value obtained as described above isfed back to the correction calculation part, each air flow rate value isconverted into a highly accurate value with few errors such asdeteriorating with the passage of time corrected by new correction. Inaddition, the appropriate fault diagnosis as described above becomespossible. Although each air flow rate values have been compared as avalue of air flow rate for each specific revolution speed in thisembodiment, it is possible to compare by using the mean value and theintegrated value within the fixed time, or a value close to the meanvalue obtained by delaying through a filter, where the controlledvariable per the revolution speed is output by inputting the enginespeed.

In the flow chart of FIG. 22, although it is assumed the processingalways go through the correction, the comparison and the judgment, it ispossible to perform their processing every fixed period of time or onlyunder the specific engine condition without always doing the processingof the comparison, the judgment, and the correction, etc., where thecontrol variable is obtained by using, for example, Qafs.

FIG. 23 is a model chart showing the operational state of theelectronically controlled throttle body integrated air flow sensoraccording to one embodiment of the present invention.

The axis of abscissa designates the running hours of the internalcombustion engine which has the system of the present invention, and theordinate designates the value of Qafs, QNρ, and QαN as the air flowrate. ◯ sign 202 in figure shows the air flow rate Qafs obtained by theair flow sensor at each time (case), and □ sign 203 shows the air flowrate value QNρ by the speed-density method, and Δ sign shows the airflow rate value QαN by the α−N method. the correction-unnecessary range213, that is, the range where each air flow rate value is almost equal,and the non-breakdown judgment range 214, that is, the range torecognize as the breakdown of the sensor which relates to the air flowrate detection when a different air flow rate value more than this rangeis indicate are shown in each case. Further, the transition model of theactual air flow rate is shown by solid line 210 as the referencealthough it is not possible substantially to detect by the system. Thetransition of Qafs at the time points when the comparison and judgmentare not performed is shown in dotted line 212. In this model, thecontrol is always performed by the Qafs, and the comparison, thejudgment, and the correction are made under the specific condition orevery certain period.

In case 1, because the all values of Qafs, QNp, and QαN are incorrection-unnecessary ranges 213, Qafs is used as the representativevalue for the controlled variable operation. Neither the correction northe breakdown judgment are performed. In case 2, the correction value ofQNρ is calculated because QNρ indicates the value different from Qafs orQαN and it becomes outside the correction-unnecessary range. Here, thecorrection of QNρ shows the example of the correction like becoming thesame value as QαN which is a value close to QNp among other air flowrate values. However, it is possible to take the mean value of two orthe same value as Qafs. Case 3 shows the state that Qafs, QNp, and QαNalmost become equal again because the correction is added to QNρ. If thecomparison, the judgment, and the correction is made under the specificcondition, it is possible to make the comparison, the judgment, and thecorrection under the stable condition of the actual air flow rate likethe above-mentioned case. However, the comparison, the judgment, and thecorrection can be done when the actual air flow rate has changed likecase 4, in case that they are always done or they are done after acertain period.

It is also possible to expand the correction-unnecessary range or thenon-breakdown judgment range in as transitional state as case 5 and tojudge because the difference between respective air flow rate detectionvalues can grow in such a transitional state. In case 6, QαN is greatlydifferent from Qafs and QNp, and it exceeds the non-breakdown judgmentrange. In this case, the fault signal of the throttle valve openingsensor is output. Case 7 shows the state that each air flow rate fallsagain in the correction-unnecessary range because the throttle valveopening sensor is exchanged. In case 8, Qafs becomes outside thecorrection-unnecessary range, and the correction is made.

As for subsequent case 9 and case 10, the fault signal of the air flowsensor is output because the Qafs exceeds the correction-unnecessaryrange again. When the same air flow rate value exceeds frequently thecorrection-unnecessary range, the sensor which affects the air flow ratevalue can be diagnosed to break down even if the air flow rate value iswithin the non-breakdown judgment range. Further, when Qafs exceeds thecorrection-unnecessary range, the QNp is used to calculate thecontrolled variable in this model. Of course, another air flow ratevalue can be used, and the mean value can be also used. Giving priorityin order with a high measuring accuracy, and using it for the controlledvariable calculation and the correction calculation standard areeffective usually.

FIG. 24 shows one embodiment in which the present invention is appliedto the internal combustion engine of the electronic fuel injection type.Intake air 301 taken from air cleaner 300 is inhaled into enginecylinder 307 through air intake duct 303, electronically controlledthrottle body integrated air flow sensor 304 provided with microcomputer313, and manifold 306 provided with injector 305 for supplying the fuel.On the other hand, gas 308 generated by engine cylinder 307 is exhaustedthrough exhaust manifold 309.

ECU 302 which inputs the corrected air flow rate signal 315 output fromthe electronically controlled throttle body integrated air flow sensor304, throttle valve opening signal 316, engine speed signal 314, andoxygen density signal 317 output from oxygen analyzer 310 provided inexhaust manifold 309 calculates the best injection quantity according toair flow rate signals 315, makes the signal value to be injector controlsignal 318, and controls said injector 305. On the other hand,electronically controlled throttle body integrated air flow sensor 304controls the electronically controlled throttle valve according toaccelerator opening signal 319 by using microcomputer 313 in circuitmodule 312, and controls the air flow rate introduced into the internalcombustion engine.

What is claimed is:
 1. An integrated air flow sensor comprising: a bodyforming air passage, an air flow rate detection means for detecting theair flow rate which flows in said air passage, and a throttle meanscontrolled with an electric signal, for limiting said air flow rate byreducing the flow, said body, said air flow rate detection means andsaid throttle means being integrated; further comprising a correctionand control means for correcting an input signal from said air flow ratedetection means and controlling said throttle means.
 2. An integratedair flow sensor according to claim 1, wherein said correction andcontrol means makes said correction based on said reduction amount. 3.An integrated air flow sensor according to claim 1, wherein saidcorrection and control means controls said throttle means so that thevalue of the signal after said correction is made may approach thetarget value.
 4. An integrated air flow sensor according to claim 1,wherein said correction and control means calculates a second air flowrate based on the engine speed and said reduction amount, and outputs aspecific signal when the difference between the signal value after saidcorrection and the second air flow rate is more than the fixed value. 5.An integrated air flow sensor according to claim 1, wherein saidcorrection and control means calculates a second air flow rate based onthe engine speed and said reduction amount, and outputs said second airflow rate signal when the difference between the signal value after saidcorrection and the second air flow rate is more than the fixed value. 6.An integrated air flow sensor according to claim 1, wherein saidcorrection and control means calculates a second air flow rate based onthe engine speed and said reduction amount and outputs it, when saidreduction amount is below the fixed value.
 7. An integrated air flowsensor according to claim 1, wherein said correction and control meanscorrects said second air flow rate based on the input air temperature.8. An integrated air flow sensor according to claim 5, wherein saidengine speed is detected based on the change in the value of the airflow rate signal detected in said air flow rate detection means.
 9. Anintegrated air flow sensor according to claim 1, further comprising athermosensitive resistor exposed to said air flow, wherein said airtemperature is calculated by using an electric current which flows insaid thermosensitive resistor or a voltage applied to both ends of saidthermosensitive resistor.
 10. An integrated air flow sensor according toclaim 1, wherein said air flow rate detection means detects the air flowrate based on the amount of heat radiation from the resistor whichgenerates heat, said throttle means is an electronically controlledthrottle, and said correction and control means is an electric circuitprovided with the microcomputer.
 11. An engine control systemcomprising: the integrated air flow sensor according to claim 1, and anengine control means for inputting a signal from said integrated airflow sensor, and controlling the amount of fuel supplied to an enginebased on said signal.
 12. An integrated air flow sensor comprising: abody forming air passage, an air flow rate detection means for detectingthe air flow rate which flows in said air passage, and a throttle meanscontrolled with an electric signal, for limiting said air flow rate byreducing the flow, said body, said air flow rate detection means andsaid throttle means being integrated; further comprising a pressurecalculation means for calculating the pressure from the air flow ratedetected by said air flow rate detection means, the engine speed, thereduction amount by said throttle means and the air temperature.
 13. Anintegrated air flow sensor according to claim 12, wherein said enginespeed is detected based on the change in the value of the air flow ratesignal detected in said air flow rate detection element.
 14. Anintegrated air flow sensor according to claim 12, further comprising athermosensitive resistor exposed to said air flow, wherein said airtemperature is calculated by using an electric current which flows insaid thermosensitive resistor or a voltage applied to both ends of saidthermosensitive resistor.
 15. An integrated air flow sensor according toclaim 12, wherein said air flow rate detection element detects the airflow rate based on the amount of heat radiation from the resistor whichgenerates heat, said throttle body is an electronically controlledthrottle, and said correction and control arrangement is an electriccircuit provided with the microcomputer.
 16. An integrated air flowsensor comprising: a body forming air passage, an air flow ratedetection means for detecting the air flow rate which flows in said airpassage, and a throttle means controlled with an electric signal, forlimiting said air flow rate by reducing the flow, said body, said airflow rate detection means and said throttle means being integrated;further comprising a air flow rate calculation means for calculating thecorrected air flow rate from the air flow rate detected by said air flowrate detection means, the engine speed, the reduction amount by saidthrottle means and the air temperature.
 17. An integrated air flowsensor according to claim 16, wherein said engine speed is detectedbased on the change in the value of the air flow rate signal detected insaid air flow rate detection element.
 18. An integrated air flow sensoraccording to claim 16, further comprising a thermosensitive resistorexposed to said air flow, wherein said air temperature is calculated byusing an electric current which flows in said thermosensitive resistoror a voltage applied to both ends of said thermosensitive resistor. 19.An integrated air flow sensor according to claim 16, wherein said airflow rate detection element detects the air flow rate based on theamount of heat radiation from the resistor which generates heat, saidthrottle body is an electronically controlled throttle, and saidcorrection and control arrangement is an electric circuit provided withthe microcomputer.
 20. An integrated air flow sensor comprising: a bodyforming air passage, an air flow rate detection means for detecting theair flow rate which flows in said air passage, and a throttle meanscontrolled with an electric signal, for limiting said air flow rate byreducing the flow, said body, said air flow rate detection means andsaid throttle means being integrated; further comprising an air flowrate calculation means for calculating the filtered air flow rate whenthe change speed in the reduction amount by said throttle means is lessthan a certain fixed value.
 21. An integrated air flow sensorcomprising: a body forming air passage, an air flow rate detection meansfor detecting the air flow rate which flows in said air passage, and athrottle means controlled with an electric signal, for limiting said airflow rate by reducing the flow, said body, said air flow rate detectionmeans and said throttle means being integrated; further comprising anair flow rate calculation means for calculating the corrected air flowrate when the change speed in the reduction amount by said throttlemeans is more than a certain fixed value.
 22. An integrated air flowsensor comprising: a body forming air passage, an air flow ratedetection means for detecting the air flow rate which flows in said airpassage, and a throttle means controlled with an electric signal, forlimiting said air flow rate by reducing the flow, said body, said airflow rate detection means and said throttle means being integrated;further comprising two or more correction maps, and an air flow ratecalculation means for calculating the air flow rate by using thecorrection map selected from said plural maps by an external signal. 23.An integrated air flow sensor according to claim 22, wherein theselection of the correction map is carried out once for all.
 24. Anintegrated air flow sensor according to claim 22, wherein the selectionof the correction map is able to change only when a specific conditionis satisfied.
 25. An integrated air flow sensor comprising: a bodyforming air passage, an air flow rate detection means for detecting theair flow rate which flows in said air passage, and a throttle meanscontrolled with an electric signal, for limiting said air flow rate byreducing the flow, said body, said air flow rate detection means andsaid throttle means being integrated; further comprising a circuit whichcan perform the detection of said air flow rate and the control of saidthrottle means together.
 26. An integrated air flow sensor comprising: abody forming air passage, an air flow rate detection means for detectingthe air flow rate which flows in said air passage, and a throttle meanscontrolled with an electric signal, for limiting said air flow rate byreducing the flow, said body, said air flow rate detection means andsaid throttle means being integrated; further comprising a correctionand control means for performing the correction of signals from said airflow rate detection means and pressure detection means and the controlof said throttle means.
 27. An integrated air flow sensor according toclaim 26, wherein said correction and control means corrects the signalfrom said pressure detection means based on said reduction amount. 28.An integrated air flow sensor according to claim 26, wherein saidcorrection and control means controls said throttle means so that thesignal of said pressure detection means may be made to approach thetarget value.
 29. An integrated air flow sensor according to claim 26,wherein said correction and control means calculates a second air flowrate based on the engine speed and said reduction amount, calculates athird air flow rate based on the engine speed and the detection value ofsaid pressure detection means, compares the first flow rate by said flowdetection means, said second air flow rate and said third air flow rate,and outputs a specific signal when any one of values is different bymore than the fixed value.
 30. An integrated air flow sensor accordingto claim 26, wherein said correction and control means calculates asecond air flow rate based on the engine speed and said reductionamount, calculates a third air flow rate based on the engine speed andthe detection value of said pressure detection means, compares the firstflow rate by said flow detection means, said second air flow rate andsaid third air flow rate, and outputs said second or third air flow ratesignal when the difference between said first air flow rate and otherair flow rate is more than the fixed value.
 31. An integrated air flowsensor according to claim 26, wherein said correction and control meanscalculates a second air flow rate based on the engine speed and saidreduction amount, calculates a third air flow rate based on the enginespeed and the detection value of said pressure detection means, comparesthe first flow rate by said flow detection means, said second air flowrate and said third air flow rate, and performs the correction ofdisplacement of the air flow rate, fault diagnosis, or the determinationof the optimum air flow rate when the measurement values of any one ofsaid first to third air flow rate measurement devices is different bymore than the fixed value.
 32. An integrated air flow sensor accordingto claim 26, wherein said correction and control means calculates athird air flow rate based on the engine speed and said pressuredetection means and outputs it, when said reduction amount is below thefixed value.
 33. An integrated air flow sensor according to claim 29,wherein said correction and control means corrects said second and saidthird air flow rate based on the input air temperature.
 34. Anintegrated air flow sensor comprising: a body forming air passage, anair flow rate detection means for detecting the air flow rate whichflows in said air passage, a throttle means controlled with an electricsignal, for limiting said air flow rate by reducing the flow, and apressure detection means for detecting the pressure at the downstream ofsaid throttle means, said body, said air flow rate detection means, saidthrottle means and said pressure detection means being integrated;further comprising an air flow rate calculation means for calculatingthe corrected air flow rate pressure from the air flow rate detected bysaid air flow rate detection means, the pressure detection means fordetecting the pressure at the downstream of said throttle means, theengine speed, the reduction amount by said throttle means and the airtemperature.
 35. An integrated air flow sensor according to claim 34,wherein said engine speed is detected based on the change in the valueof the air flow rate signal detected in said air flow rate detectionmeans.
 36. An integrated air flow sensor according to claim 34, whereinsaid engine speed is detected based on the change in the value of thepressure signal detected in said pressure detection means.
 37. Anintegrated air flow sensor according to claim 34, wherein said airtemperature is calculated by using an electric current which flows insaid thermosensitive resistor or a voltage applied to both ends of saidthermosensitive resistor.
 38. An integrated air flow sensor according toclaim 34, wherein said air flow rate detection means detects the airflow rate based on the amount of heat radiation from the resistor whichgenerates heat, said throttle means is an electronically controlledthrottle, said pressure detection means is a semiconductor type pressuredetection device and said correction and control means is an electriccircuit provided with the microcomputer.